— How many of you have solved the math problem?—________, the math problem is far too difficult for us to work out..
A: When do you usually have dinner? B: ____6:30____the evening.
I like English, ____ I am not good at it.
There is ____ office on the first floor(一楼).
A: Is the pen on the desk?B: ____.
A: Is there a computer in your class?B: ____.